The PKN1- TRAF1 signaling axis as a potential new target for chronic lymphocytic leukemia.

TRAF1 is a pro-survival adaptor molecule in TNFR superfamily (TNFRSF) signaling. TRAF1 is overexpressed in many B cell cancers including refractory chronic lymphocytic leukemia (CLL). Little has been done to assess the role of TRAF1 in human cancer. Here we show that the protein kinase C related kinase Protein Kinase N1 (PKN1) is required to protect TRAF1 from cIAP-mediated degradation during constitutive CD40 signaling in lymphoma. We show that the active phospho-Thr774 form of PKN1 is constitutively expressed in CLL but minimally detected in unstimulated healthy donor B cells. Through a screen of 700 kinase inhibitors, we identified two inhibitors, OTSSP167, and XL-228, that inhibited PKN1 in the nanomolar range and induced dose-dependent loss of TRAF1 in RAJI cells. OTSSP167 or XL-228 treatment of primary patient CLL samples led to a reduction in TRAF1, pNF-κB p65, pS6, pERK, Mcl-1 and Bcl-2 proteins, and induction of activated caspase-3. OTSSP167 synergized with venetoclax in inducing CLL death, correlating with loss of TRAF1, Mcl-1, and Bcl-2. Although correlative, these findings suggest the PKN1-TRAF1 signaling axis as a potential new target for CLL. These findings also suggest the use of the orally available inhibitor OTSSP167 in combination treatment with venetoclax for TRAF1 overexpressing CLL.

Creating a Competency-Based Medical Education Curriculum for Canadian Diagnostic Radiology Residency (Queen's Fundamental Innovations in Residency Education)-Part 1: Transition to Discipline and Foundation of Discipline Stages.

PURPOSE: The Royal College of Physicians and Surgeons of Canada (RCPSC) has mandated the transition of postgraduate medical training in Canada to a competency-based medical education (CBME) model divided into 4 stages of training. As part of the Queen's University Fundamental Innovations in Residency Education proposal, Queen's University in Canada is the first institution to transition all of its residency programs simultaneously to this model, including Diagnostic Radiology. The objective of this report is to describe the Queen's Diagnostic Radiology Residency Program's implementation of a CBME curriculum. METHODS: At Queen's University, the novel curriculum was developed using the RCPSC's competency continuum and the CanMEDS framework to create radiology-specific entrustable professional activities (EPAs) and milestones. In addition, new committees and assessment strategies were established. As of July 2015, 3 cohorts of residents (n = 9) have been enrolled in this new curriculum. RESULTS: EPAs, milestones, and methods of evaluation for the Transition to Discipline and Foundations of Discipline stages, as well as the opportunities and challenges associated with the implementation of a competency-based curriculum in a Diagnostic Radiology Residency Program, are described. Challenges include the increased frequency of resident assessments, establishing stage-specific learner expectations, and the creation of volumetric guidelines for case reporting and procedures. CONCLUSIONS: Development of a novel CBME curriculum requires significant resources and dedicated administrative time within an academic Radiology department. This article highlights challenges and provides guidance for this process.

Constitutive interaction between 4-1BB and 4-1BBL on murine LPS-activated bone marrow dendritic cells masks detection of 4-1BBL by TKS-1 but not 19H3 antibody.

4-1BB is a TNFR family member associated with NF-κB mediated survival signaling. 4-1BB is widely expressed on activated cells of the immune system, including activated T cells, NK cells and dendritic cells. Its ligand, 4-1BBL, is transiently expressed on activated antigen presenting cells and at low levels on activated T cells. Although 4-1BBL-deficient mice clearly demonstrate a role for 4-1BBL in CD8 T cell responses to viruses such as influenza, 4-1BBL can be difficult to detect following infection of mice. Here we provide evidence for a constitutive interaction between endogenous 4-1BB and 4-1BBL on LPS activated bone marrow-derived murine dendritic cells that can mask its detection, with implications for measurement of 4-1BBL expression. The masking of 4-1BBL by its receptor results in loss of reactivity to the anti-4-1BBL antibody TKS-1, whereas the 19H3 antibody binds to 4-1BBL in the presence or absence of 4-1BB. Moreover, 4-1BB/4-1BBL interaction can occur in trans between 4-1BB+/+ and 4-1BB-/- dendritic cells in culture. These data suggest that 19H3 is the preferable antibody to use to detect 4-1BBL in the presence of its receptor.

Irreversible splenic atrophy following chronic LCMV infection is associated with compromised immunity in mice.

Lymphocytic choriomeningitis virus clone 13 (LCMV13) infection of mice is a widely used model for investigating the mechanisms driving persistent viral infection in humans. LCMV13 disrupts splenic architecture early during infection, but this returns to normal within a few weeks. However, the long-term effects of LCMV13 infection on splenic structure have not been reported. Here, we report that persistent infection with LCMV13 results in sustained splenic atrophy that persists for at least 500 days following infection, whereas infection with the acutely infecting LCMV Armstrong is associated with a return to preinfection spleen weights. Splenic atrophy is associated with loss of T, B, and non-B non-T cells, with B cells most significantly affected. These effects were partly ameliorated by anti-NK1.1 or anti-CD8 antibody treatment. Antigen presentation was detectable at the time of contraction of the spleen, but no longer detected at late time points, suggesting that continued antigen presentation is not required to maintain splenic atrophy. Immunity to Salmonella infection and influenza vaccination were decreased after the virus was no longer detected. Thus splenic atrophy following LCMV13 infection is irreversible and may contribute to impaired immunity following clearance of LCMV13.

The signaling adaptor TRAF1 negatively regulates Toll-like receptor signaling and this underlies its role in rheumatic disease.

TRAF1 is a signaling adaptor known for its role in tumor necrosis factor receptor-induced cell survival. Here we show that monocytes from healthy human subjects with a rheumatoid arthritis-associated single-nucleotide polymorphism (SNP) in the TRAF1 gene express less TRAF1 protein but greater amounts of inflammatory cytokines in response to lipopolysaccharide (LPS). The TRAF1 MATH domain binds directly to three components of the linear ubiquitination (LUBAC) complex, SHARPIN, HOIP and HOIL-1, to interfere with the recruitment and linear ubiquitination of NEMO. This results in decreased NF-κB activation and cytokine production, independently of tumor necrosis factor. Consistent with this, Traf1-/- mice show increased susceptibility to LPS-induced septic shock. These findings reveal an unexpected role for TRAF1 in negatively regulating Toll-like receptor signaling, providing a mechanistic explanation for the increased inflammation seen with a disease-associated TRAF1 SNP.

Costimulatory TNFR family members in control of viral infection: outstanding questions.

Members of the TNFR family can play prominent roles in controlling the magnitude, duration and phenotype of the immune response to viruses. The importance of particular TNFRs in different viral infections and whether they contribute to viral control or pathology is dependent on the virus and the severity of the infection. TNFRs and their ligands are widely and differentially expressed on both adaptive and innate immune cell types. The cell types through which TNFRs exert their effects, the unique signals provided by each member of the family, and how these signals are ultimately integrated during an anti-viral immune response remain to be fully elucidated. Here we discuss the role of 4-1BB, OX40, CD27 and GITR and their ligands during viral infection and highlight some of the outstanding questions in the field.

Contribution of 4-1BBL on radioresistant cells in providing survival signals through 4-1BB expressed on CD8⁺ memory T cells in the bone marrow.

The persistence of memory lymphocytes is a critical feature of adaptive immunity. The TNF family ligand 4-1BBL supports the antigen-independent survival of CD8⁺ memory T cells. Here, we show that mice lacking 4-1BB only on αß T cells show a similar defect in CD8⁺ T-cell recall responses, as previously shown in 4-1BBL-deficient mice. We show that 4-1BB is selectively expressed on BM CD8⁺ but not CD4⁺ memory T cells of unimmunized mice. Its ligand, 4-1BBL, is found on VCAM-1⁺ stromal cells, CD11c⁺ cells, and a Gr1(lo) myeloid population in unimmunized mice. Adoptive transfer of in vitro generated memory T cells into mice lacking 4-1BBL only on radioresistant cells recapitulates the defect in CD8⁺ T-cell survival seen in the complete knockout mice, with smaller effects of 4-1BBL on hematopoietic cells. In BM, adoptively transferred DsRed CD8⁺ memory T cells are most often found in proximity to VCAM-1⁺ cells or Gr1⁺ cells, followed by B220⁺ cells and to a much lesser extent near CD11c⁺ cells. Thus, a VCAM-1⁺CD45(-) stromal cell is a plausible candidate for the radioresistant cell that provides 4-1BBL to CD8⁺ memory T cells in the BM.